bmpdec: support for rgb444 with bitfields compression

Do not display garbage for invalid/unsupported bitfields values.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

libavcodec/bmp.c

@@ -162,8 +162,18 @@ static int bmp_decode_frame(AVCodecContext *avctx,
     case 16:
         if(comp == BMP_RGB)
             avctx->pix_fmt = PIX_FMT_RGB555;
-        if(comp == BMP_BITFIELDS)
-            avctx->pix_fmt = rgb[1] == 0x07E0 ? PIX_FMT_RGB565 : PIX_FMT_RGB555;
+        else if (comp == BMP_BITFIELDS) {
+            if (rgb[0] == 0xF800 && rgb[1] == 0x07E0 && rgb[2] == 0x001F)
+               avctx->pix_fmt = PIX_FMT_RGB565;
+            else if (rgb[0] == 0x7C00 && rgb[1] == 0x03E0 && rgb[2] == 0x001F)
+               avctx->pix_fmt = PIX_FMT_RGB555;
+            else if (rgb[0] == 0x0F00 && rgb[1] == 0x00F0 && rgb[2] == 0x000F)
+               avctx->pix_fmt = PIX_FMT_RGB444;
+            else {
+               av_log(avctx, AV_LOG_ERROR, "Unknown bitfields %0X %0X %0X\n", rgb[0], rgb[1], rgb[2]);
+               return AVERROR(EINVAL);
+            }
+        }
         break;
     case 8:
         if(hsize - ihsize - 14 > 0)